#include <string.h>
#include <stdlib.h>
#include <lua5.3/lualib.h>
#include <lua5.3/lauxlib.h>
#include <time.h>

#include "oct_timer.h"
#include "oct_log.h"

struct oct_timer_list_ oct_timer_list;
int64_t prev_millis;

int oct_timer_list_initialize() {
	OCT_LOG_INFO("Initializing timer list")
	oct_timer_list.size = 0;
	oct_timer_list.first = NULL;
	oct_timer_list.last = NULL;

	struct timespec now;
    timespec_get(&now, TIME_UTC);
	prev_millis = ((int64_t) now.tv_sec) * 1000 + ((int64_t) now.tv_nsec) / 1000000;
	

	return 1;
}

int oct_timer_list_deinitialize() {
	struct oct_timer_elem* crawler = oct_timer_list.first;
	while (crawler != NULL) {
		struct oct_timer_elem* temp = crawler->next;
		free(crawler);
		crawler = temp;
	}
	oct_timer_list.first = NULL;
	oct_timer_list.last = NULL;
	oct_timer_list.size = 0;

	return 1;
}

int oct_timer_register(lua_State *L) {
	// Gather the arguments
	char id[OCT_TIMER_MAXIMUM_ID_LENGTH];
	int64_t millis;
	char function[OCT_TIMER_MAXIMUM_ID_LENGTH];
	char argument[OCT_TIMER_MAXIMUM_ID_LENGTH];
	strncpy(id, luaL_checkstring(L, -4), OCT_TIMER_MAXIMUM_ID_LENGTH);
	millis = luaL_checkinteger(L, -3);
	strncpy(function, luaL_checkstring(L, -2), OCT_TIMER_MAXIMUM_FUNCTION_NAME_LENGTH);
	strncpy(argument, luaL_checkstring(L, -1), OCT_TIMER_MAXIMUM_ARGUMENT_LENGTH);

	// Check for any duplicate ids in the list
	if (oct_timer_find(id)) {
		OCT_LOG_ERROR("Tried to register a timer with a duplicate ID");
		lua_pushnil(L);
		return 1;
	}

	// We're good to go, insert at the end
	struct oct_timer_elem* e = (struct oct_timer_elem*)malloc(sizeof(struct oct_timer_elem));
	strncpy(e->id, id, OCT_TIMER_MAXIMUM_ID_LENGTH);
	e->millis = millis;
	strncpy(e->lua_function, function, OCT_TIMER_MAXIMUM_FUNCTION_NAME_LENGTH);
	strncpy(e->lua_argument, argument, OCT_TIMER_MAXIMUM_ARGUMENT_LENGTH);
	if (!oct_timer_list.first) {
		oct_timer_list.first = e;
	}
	e->next = NULL;
	e->prev = oct_timer_list.last;
	if (oct_timer_list.last) {
		oct_timer_list.last->next = e;
	}
	oct_timer_list.last = e;
	oct_timer_list.size++;

	// not sure if i have to return something
	return 0;
}

struct oct_timer_elem* oct_timer_find(char* id) {
	struct oct_timer_elem* crawler = oct_timer_list.first;
	while (crawler != NULL) {
		if (strncmp(id, crawler->id, OCT_TIMER_MAXIMUM_ID_LENGTH) == 0) {
			return crawler;
		}
		crawler = crawler->next;
	}
	return NULL;
}

int oct_timer_unregister(char* id, int do_free) {
	struct oct_timer_elem* e = oct_timer_find(id);
	if (!e) {
		OCT_LOG_WARNING("Tried to unregister a nonexistent timer");
		return 0;
	}

	if (e == oct_timer_list.first) {
		oct_timer_list.first = e->next;
		if (e->next) {
			e->next->prev = NULL;
		}
	}
	else if (e == oct_timer_list.last) {
		oct_timer_list.last = e->prev;
		if (e->prev) {
			e->prev->next = NULL;
		}
	}
	else {
		e->next->prev = e->prev;
		e->prev->next = e->next;
	}

	oct_timer_list.size--;
	
	if (do_free) {
		free(e);
	}
	
	// Not sure if I have to return something
	return 0;
}

int oct_timer_unregister_lua(lua_State *L) {
	char id[OCT_TIMER_MAXIMUM_ID_LENGTH];
	strncpy(id, luaL_checkstring(L, -1), OCT_TIMER_MAXIMUM_ID_LENGTH);
	
	int res = oct_timer_unregister(id, 1);
	if (!res) {
		lua_pushnil(L);
		return 1;
	}
	return 0;
}

int oct_timer_initialize_lua(lua_State *L) {
	OCT_LOG_INFO("Exporting timer lua functions");
	lua_pushcfunction(L, oct_timer_register);
	lua_setglobal(L, "oct_timer_register");
	lua_pushcfunction(L, oct_timer_unregister_lua);
	lua_setglobal(L, "oct_timer_unregister");
	// I don't think we need a metatable...
	return 1;
}

int oct_timer_tick(lua_State *L) {
	struct timespec now;
    timespec_get(&now, TIME_UTC);
	int64_t millis = ((int64_t) now.tv_sec) * 1000 + ((int64_t) now.tv_nsec) / 1000000;
	int64_t elapsed = millis - prev_millis;

	struct oct_timer_elem* crawler = oct_timer_list.first;
	while (crawler != NULL) {
		crawler->millis -= elapsed;
		if (crawler->millis <= 0) {
			struct oct_timer_elem* temp = crawler;
			crawler = crawler->next;
			// First, remove the timer
			// lua can add a timer at the end of the function, don't want to complicate things by making the developer come up with a unique name
			// So we unregister it, but don't free it yet
			oct_timer_unregister(temp->id, 0);
			
			// call lua function with argument
			lua_getglobal(L, temp->lua_function);
			lua_pushstring(L, temp->lua_argument);
			lua_call(L, 1, 0);

			// Now free the timer
			free(temp);
		}
		else {
			crawler = crawler->next;
		}
	}
	
	prev_millis = millis;
	return 0;
}